Dongzhi (冬至) — Winter Solstice

Dongzhi occurs at celestial longitude 270°, around December 21-23. The longest night and shortest day of the northern hemisphere year. Classical wisdom: "冬至一陽生" — at the depth of winter, yang is reborn. The "nine-nine" cold-day count begins.

Tradition: northern China eats dumplings; southern China eats glutinous rice balls (湯圓). Family reunion is emphasized — "冬至大如年" (winter solstice is as important as new year). Climate: coldest period still ahead.